December 2017 - Git, R Style Guide

How's it going so far?

As of Monday, 12 people have completed Course 1 and one person has completed Course 2.

Average progress on Course 2 is 50.6%.

How's it going so far?

As of Monday, 12 people have completed Course 1 and one person has completed Course 2.

Average progress on Course 2 is 50.6%.

What would make this experience better/easier next time?

(Vulcan mind meld isn't an option, unfortunately)

• Git vs. GitHub vs. Git BASH
• Git, GitHub, and RStudio
• Q&A
• R Coding Style Conventions

• When you open a project, pull before you make any changes
• One commit for each incremental improvement or set of changes that accomplish a single goal
• Push often
• Pull often (if multiple computers or collaborators)
• google any error messages you get!
  GitHub has great documentation!

• Configuring git on a new computer
• Other git clients - if RStudio's git interface bugs out or is slow
• Connecting to GitHub from your computer
• Setting up SSH Keys - so you don't have to type your github username/password every time
• RStudio and Git/GitHub
• New Project Workflow
• Existing Project Workflow
• Fixing unfixable problems

What isn't clear about the current material?

A set of conventions for programming that make code easily readable and sharable

NPPD will use a modified form of Google's style guide

• File Names end in .R
• Variables: variableName … should be descriptive
• Functions: function_name or FunctionName
• Lines less than 80 characters long (continue command on next line)
• Indent: use 2 spaces (no tabs)
  Tools -> Global Options -> Code in RStudio to change
• Assignment: Use <-. Do not use = or ->.
  = is used inside function calls - this is ok

• Curly Braces: first on same line, last on own line. Space between ) and {

my_fun <- function(x) {
  return(x)
}

• else: Surround with braces

x <- 3

if (x > 2) {
  y <- 4
} else {
  y <- 2
}

File Layout:

• Author
• File Description
• Library statements
• Function Definitions
• Executed Statements

# Author: Susan Vanderplas

# ------------------------------------------------------
# This file demonstrates the ideal layout of an R code 
# file. This block is for a description of the code's
# purpose and file contents. 
# ------------------------------------------------------

# --- Packages -----------------------------------------
library(ggplot2)
library(dplyr)
# ------------------------------------------------------

myfun <- function(x) {
  # This function returns the value that is passed in
  # Basically, it does nothing.
  # Args:
  #   x: The value to be returned
  # Returns: 
  #   x: The value passed in to the function

  return(x)
}

# This code executes myfun on the value 3
myfun(3)

• Errors: stop() or stopifnot() should be used to generate errors
• Warnings: warning("Message goes here") should be used to generate warnings
• Messages: message("Message goes here") should be used to generate messages.
  • Debugging messages are useful, but should be commented out when code is ready for production.